Passive Design Strategies Help Mixed-Use Owners Maximize Sustainability, Energy Savings
At a conceptual and theoretical level, all architects support sustainability and want to make the world a better, greener place. Some states, such as California, have gone as far as establishing sustainability requirements — many that go far beyond industry standards — to ensure new buildings are designed with the environment in mind.
California, for example, has the nation’s first mandatory green building standards code, CALGreen Code. This is in addition to Title 24 Energy Standards, which implement minimum energy-efficiency standards and are referenced within the LEED certification system.
In California and many other states, LEED is no longer driving sustainable design, as many of the program’s basic principles have become common practice. In addition to CALGreen Code, California has adopted a new goal far tougher than LEED’s requirements: Zero Net Energy (ZNE), which is a label reserved for energy-efficient buildings whose actual annual consumed energy is less than or equal to the renewable energy generated onsite.
The state’s goals for the development of ZNE buildings must be implemented in new residential construction by 2020 and commercial construction by 2030.
While architects and designers in California are obligated to follow these strict requirements, building design professionals in the Southeast and other parts of the country can become early — and voluntary — adopters of the same principles. Those who do will place themselves at the forefront of the growing sustainable build movement, delivering next-generation projects that appeal to forward-looking users.
Here are three passive design strategies that architects can incorporate in mixed-use buildings to help achieve these results:
Proper Solar Orientation
Orienting a building correctly doesn’t require new technology or costly materials. The ultimate goal is to ensure the building is sited in such a way that it works with the sun and not against it. Architects have been doing this for millennia.
This makes a huge impact because siting the building to work with the sun helps lessen heat gain or loss. As a result, all other sustainability features work more efficiently, which in addition to reducing a building’s carbon footprint will result in lower energy bills.
When properly orienting the building, architects consider seasonal variations in the sun’s path as well as wind patterns. In the hot and oftentimes humid climates of the Southeast, architects attempt to avoid direct sunlight by using trees and nearby buildings for shade, as well as recessed windows, overhangs and canopies to physically block the sun.
While mitigating the sun’s impact can limit creative opportunities in siting the building on the lot, it’s less of a problem in a mixed-use project than it is in tract-home residential development, where each house is like a widget inserted into the site plan. In those instances, the goal is to maximize the number of units on the property, not to achieve proper solar orientation, which can make it difficult to attain the desired level of sustainability.
Window technology has improved significantly in the last decade. The single-pane aluminum windows of the past wreaked havoc on buildings’ HVAC systemS. Fortunately, high-performance vinyl windows are now available, as are double- and triple-pane windows with coatings or infill gases that are extremely energy-efficient. These high-performance windows are available today at a reasonable cost, so developers don’t have to compromise design to stay within budget.
In some cases, a little creativity is all that’s needed to keep window costs down. For example, in high-density, mixed-use housing projects, standard off-the-shelf vinyl window systems are used, and the manufacturer combines windows to create systems as large as eight feet wide by six feet tall to meet design specs.
These systems have the appearance of high-end custom windows but are actually constructed from standard residential windows that offer the mandated level of performance, making them a cost-effective alternative.
Selecting an efficient window system goes hand-in-hand with establishing proper solar orientation. If the latter is missing, higher performance windows are often required, which drives up project costs.
As windows have evolved, so has insulation. Over the last 10-plus years, the industry has come a long way from the pink fiberglass batting that used to be standard.
Insulation is crucial to energy efficiency and sustainability because it stops the movement of air. Its use in roofs, ceilings, walls and floors prevents air from entering or leaving the building and, as a result, helps to keep interior temperatures at desired levels.
Today, architects can choose from a new assortment of insulation products including sprayed insulation and rigid foam products that are more effective at sealing the entire wall without the gaps that were common with fiberglass. Over time, prices on these alternative products have come down to a point where the differential in cost has been minimized, allowing the architect to choose the product that will achieve the most energy-efficient option for the project, thereby reducing the operating costs for the building.
The Bottom Line
It’s often possible to incorporate all three of these passive design principles into a project, such as The Maxwell, a six-story mixed-use project in Arlington, Virginia. Designed by KTGY and certified LEED Gold, the building hugs the street edge in an L-shaped configuration with the main street frontages on the north and west sides of the site, sheltering an internal courtyard for residents. Vehicles enter on the south side of the building.
Every window system is recessed at least two inches with horizontal canopy elements serving as solar shading devices over some of the window systems. The windows are located in strategic locations for design and performance purposes. Additionally, a continuous rigid roof insulation and cavity wall insulation were used in the apartment and retail project. By incorporating these passive design principles, the energy savings for the project were 38 percent greater than a comparable building in which these design elements were not employed.
Proper solar orientation, high-tech windows and insulation have the power to enhance the value of a mixed-use project, both literally and figuratively. Financially speaking, reduced energy requirements mean a building’s operating costs will also decline. That ultimately leads to higher net operating income, thereby increasing the building’s value at sale.
Of course, these features also benefit the occupants of both residential and commercial buildings, as energy savings can be passed on to tenants, making everything from apartments to offices easier to fill. And while individual sustainability elements may not be the deciding factor in a lease — after all, few care about what type of insulation is used as long as they’re comfortable — when taken as a whole, they can help a property achieve certain benchmarks that serve as a differentiator in the marketplace.
There’s likely to be resistance to these types of changes due to rising construction costs, especially when they aren’t mandated by state code. But, as architects, it’s our responsibility to push the design envelope, and sometimes it’s what the eye can’t see that matters most.
— By Ben Kasdan, associate principal, KTGY Architecture + Planning. This article originally appeared in the October issue of Southeast Real Estate Business magazine.